Barracuda Legend Kit Problems

[Old cart]

Thanks to all for the help

Thanks to all who are helping here. It is good see international cooperation working so well. Too bad the larger world is not so cooperative.

I appreciate the difficulties non English speakers have, it must hard to have to translate everything.

I find the the different communication styles fascinating but it is good that we can have healthy debates without getting into real fights!

Cheers

[Old cart]

Hi Qiaozhi,

The only differences that I can spot are minor: a buzzer rather than a headset socket; a 20K pot replacing both R27 and R29. (My R21 was 390 rather than 330ohms, but another post suggested this was not usual).

It would be wonderful if this was added to the Sticky, tagged as the Silverdog kit version. I gave up trying to read the hand drawn schema in the zip file. It is just not a very clear digital copy.

I failed to pick out this schema to work with, instead picking the latest posted. The differences were very confusing, but ultimately I've learnt more.☺

Ray

Ray the 390 vS 330 ohms can make quite a difference. Not for troubleshooting but for optimizing. On my detector critically damping the finished coil, adjusting the offset and carefully adjusting the delay gives 30% more depth. This is more than all other changes I have made combined!
We will optimize that later once the coil is finalized, that is, if you wish.

[ivconic]

Thanks to all who are helping here. It is good see international cooperation working so well. Too bad the larger world is not so cooperative.

I appreciate the difficulties non English speakers have, it must hard to have to translate everything.

I find the the different communication styles fascinating but it is good that we can have healthy debates without getting into real fights!

Cheers

Indeed too bad! World would be a better place if it was based on enthusiasm like we are having it here.

"... the difficulties non English speakers ..."

Actually, the language itself is not a problem. It is easy to learn and understand. No need for translators. At least i don't use them at all in last dozen years.
What can be problem from time to time is not the language but the context and a way of thinking.
Different people, different minds, different way of thinking and expressing here.
And over the top there is also a "modern" way of talking; using too much abbreviations!
Internet introduced too many funny and crazy abbreviations lately. Sometimes it is problem to connect all those together in a thought which is making any sense!
And additional obstacle may be difference in education and different levels of knowledge here.
Highly educated and conversant people can easily understand each other with use of strictly "technical" language and common professional phrases and terms.
Lightly educated enthusiasts and hobbyists (my category) however will need a bit of more "human" explanations and help to understand some of the articles.
So it's not always about language, pretty often is about many other "side" factors.

[Qiaozhi]

Hi Qiaozhi,

The only differences that I can spot are minor: a buzzer rather than a headset socket; a 20K pot replacing both R27 and R29. (My R21 was 390 rather than 330ohms, but another post suggested this was not usual).

It would be wonderful if this was added to the Sticky, tagged as the Silverdog kit version. I gave up trying to read the hand drawn schema in the zip file. It is just not a very clear digital copy.

I failed to pick out this schema to work with, instead picking the latest posted. The differences were very confusing, but ultimately I've learnt more.☺

Ray

Well ... we will find out soon!
Impulse is sending me his Baracuda PCB (with coil and cable) for testing, so we'll get to the bottom of this in the near future.
Once testing is complete I will post a sticky with the official schematic, and ask Silverdog to put it on his website as well.

[ivconic]

Ray the 390 vS 330 ohms can make quite a difference. Not for troubleshooting but for optimizing. On my detector critically damping the finished coil, adjusting the offset and carefully adjusting the delay gives 30% more depth. This is more than all other changes I have made combined!
We will optimize that later once the coil is finalized, that is, if you wish.

R21 is depending mostly on coil.
It's value certainly can make a difference, because if it was not chosen properly; coil will ring.
It is easy to see on scope while adjusting the damping value.
Major trouble there is to obtain precise value which would ideally fit actual coil.
Pretty often common values are not perfect match.
I noticed that not so many people do pay special attention on this.
And offset too.
But precisely at Barracuda i noticed interesting thing; static mode will not work properly if offset is not perfectly adjusted.
That's why we seen several cases where is advised to omit that fet and few components around it, simply because many people didn't managed to make it work properly.
So i adopted pretty funny method to solve this; i wire it up in static mode, put Tune and Delay in middle positions and than fine readjust offset at front end (by listening audio response).
And it works! Sweet and easy!
Now is up to more "technical" people here to explain why it works that way!

[Old cart]

R21 is depending mostly on coil.
It's value certainly can make a difference, because if it was not chosen properly; coil will ring.
It is easy to see on scope while adjusting the damping value.
Major trouble there is to obtain precise value which would ideally fit actual coil.
Pretty often common values are not perfect match.
I noticed that not so many people do pay special attention on this.
And offset too.
But precisely at Barracuda i noticed interesting thing; static mode will not work properly if offset is not perfectly adjusted.
That's why we seen several cases where is advised to omit that fet and few components around it, simply because many people didn't managed to make it work properly.
So i adopted pretty funny method to solve this; i wire it up in static mode, put Tune and Delay in middle positions and than fine readjust offset at front end (by listening audio response).
And it works! Sweet and easy!
Now is up to more "technical" people here to explain why it works that way!

Agreed about the damping resistor. Easy to adjust if you have a good scope that does not load the circuit and monitor the input AND output of the preamp at the same time. Final tuning usually has to be done either by looking just at the output.
The comment on the static mode of Baracuda is easy to understand now that you have explained it. You should probably set the DC offset in the static mode because DC current passes then. When you release the button it is AC coupled and the DC offset has only a minor effect. That is essentially what you are doing. Thanks for the hint.

In either case offset can have a minor effect on preamp output waveshape because it affects the operating point of the preamp.

[ivconic]

[Old cart]

Well ... we will find out soon!
Impulse is sending me his Baracuda PCB (with coil and cable) for testing, so we'll get to the bottom of this in the near future.
Once testing is complete I will post a sticky with the official schematic, and ask Silverdog to put it on his website as well.

Very interested to hear what you find out. Do you plan on checking ours the incorrect pull up reference we have been discussing?

[Old cart]

Indeed too bad! World would be a better place if it was based on enthusiasm like we are having it here.

"... the difficulties non English speakers ..."

Actually, the language itself is not a problem. It is easy to learn and understand. No need for translators. At least i don't use them at all in last dozen years.
What can be problem from time to time is not the language but the context and a way of thinking.
Different people, different minds, different way of thinking and expressing here.
And over the top there is also a "modern" way of talking; using too much abbreviations!
Internet introduced too many funny and crazy abbreviations lately. Sometimes it is problem to connect all those together in a thought which is making any sense!
And additional obstacle may be difference in education and different levels of knowledge here.
Highly educated and conversant people can easily understand each other with use of strictly "technical" language and common professional phrases and terms.
Lightly educated enthusiasts and hobbyists (my category) however will need a bit of more "human" explanations and help to understand some of the articles.
So it's not always about language, pretty often is about many other "side" factors.

Good points Ivconic but you ARE an English speaker! Indeed your English is better than many Americans.

[Qiaozhi]

Very interested to hear what you find out. Do you plan on checking ours the incorrect pull up reference we have been discussing?

Yes - I intend to check everything.

[ivconic]

Good points Ivconic but you ARE an English speaker! Indeed your English is better than many Americans.

Speaking of "speaking"....

P.S.
Thanks to Davor!

[raygdunn]

Ray the 390 vS 330 ohms can make quite a difference. Not for troubleshooting but for optimizing. On my detector critically damping the finished coil, adjusting the offset and carefully adjusting the delay gives 30% more depth. This is more than all other changes I have made combined!
We will optimize that later once the coil is finalized, that is, if you wish.

Any more depth would be very nice. I had assumed it was more about faster decay times. I did this on the PI-1, but didn't test range before and after.

I saw 390 ohms as a useful change, as would need increasing anyway and I've seen no signs of oscillations on a pretty standard wind 10" coil. I furvently hope Qiaozhi can figure out that coil movement problem, so I can really up that resistor with a spider type coil. Way beyond me I think... Though I still have to try adding the extra components.

Ray

[raygdunn]

Here is a good example. Impulse has .55 volts on pin 1 of the 40106. This is an actual measured voltage, not a simulation. This clearly exceeds the absolute maximum input voltage rating of TI. This 40106 also is not working correctly. It introduces additional pulses that should not be there. They are runt pulses ( smaller than normal) the occur on the rising and falling edges of the transmit pulse. These may have no effect on the Baracuda operation, but they should not be there!

One simple solution would be to cut the trace that leads to the +5 volt regulator very near the 33k resistor attached to pin 1 of the 40106. Cut the trace between the 33k and the regulator NOT between the 33k and pin 1. This will allow R17,18, and 19 to float. Then tie this point to pin 14 of the 40106 with a thin jumper wire. This hold place pins 1 ,3 and 5 at 0 volts which is still a logic high and will not exceed the chip specs. However it will likely alter the timing of the two timing pulse and require resistor value adjustments.

if someone can look this over it advise if I have this right that would be great.

Well that looked a simple change, but I made a meal of it. My part replacement skills are useless. At least I've now made myself a nice hook tool from a bit of wire. Levering on adjacent components really wasn't a good idea. I probably should have done a YouTube search for methods. Also spent ages redrilling the holes with a pin drill. (Maybe the bit was not hard enough). Is there a good desoldering tool that clears the components holes?

For me the adjusted resistors are:
33K : 13.3K (two for the pulse widths). I used 10K+3K
150K : 56.6K (interpulse gap) I used 56K

So I now have:
First sample pulse: 44us (schema 45us. Original was 40us)
Pulse gap: 141us (target was 144ms to match my original)
Second sample pulse: 50us (schema 45us. Original was 40us)
<br>So I've badly matched the pulses. My conclusion is that though the sample width resistors were adjacent on the strip they must have varied. The original pulse widths I think matched fine.

Presumably zeroing NE5534 output is intended to balance this out. (It was actually only about 0.02V out)

Works fine anyway. Yet to try it in a less noisy environment.

Ray

[6666]

Also spent ages redrilling the holes with a pin drill.

If you are drilling out holes make sure you dont drill out any vias, solder wick and a solder sucker usually does a sufficient job
but if you are only reducing the value of a resistor no need to remove it, just solder another resistor in parallel, or solder in a pot.

[Koala]

If you are drilling out holes make sure you dont drill out any vias, solder wick and a solder sucker usually does a sufficient job
but if you are only reducing the value of a resistor no need to remove it, just solder another resistor in parallel, or solder in a pot.

I use to replace ICs on home computer everyday with a solder sucker. The holes on Silverdogs are quite small and tough to de solder using this method.


liquid flux + solder wick works well for me.